s/
    (                                           # Match and backreference to either
        (?:		             
            Perl|		                  # one or
            perl|                                 # another way
            PERL|                                 # to spell
            [Pp][Ee][Rr][Ll]                      # perl
        )|                                      # or
        (?:				
            Java|                                 # one or
            java|                                 # another way
            JAVA|                                 # to spell
            [Jj][Aa][Vv][Aa]                      # java
        )
    )                                 
/        # and replace it with
    lc($1) eq "perl" ?
        "$1 looks like a nice language to me"   # this when perl is found
    :lc($1) eq "java"?
        "I don't know $1 very well"             # or this when java is found
    :"I do not wish to consider $1"             # or this when something else is found.
/ex;